If you want to change entries in a standard table through debug mode then just go through the below screen shots and it will be cake walk.
Now I am going to edit Doc type of EBAN table for an entry.
Go to Transaction SE11, Input EBAN in Database table field. Click on Display.
Now click on Contents icon (ctrl+shift+F10).
I have restricted for 20 hits only.
Now select one of the entries in the output list and click on display icon.
Now Input /h as in the screen shot and click on Enter twice.
Now it will take to the debugger screen and double click on CODE as in the screen shot.
Click on shades icon in Variables 1 screen on right side, and enter EDIT as shown in the below screenshot.
Now click on F8.
Now edit the document type to the desired value you want to have.
As in the screenshot, I have selected document type RV and then save it.
Now come back to the table entries screen wherein which you can see the New/Changed value for the document type NB.